Gear shaper



y 1952 w. s. PRAEG 2,604,016

GEAR SHAPER Filed July l5, 1946 2 SHEETS-SHEET 1 INVENTOR. WALTER S. PRAEG ATTO Patented July 22, 1952 GEAR SHAPER Walter s. mtg, Detroit, flinch 'hs'ighd' tionof Vermont applicamnimiyas, 1'94s,"senarmxssiet The present invent-ion relates "to a shaping eperation'aand "has reference particularly to a shaping operationin which a *shaping =-ciitter is supportedformovement from' 'a -nc 'ut'ra'1 psit'iorr to Wonttirig position in vvhiclf-it is inclined wi-th respecvtothe path of cuttin'g s'trok so as ta -provide clearance -back of the cutting edge. W-hi1e the invention is applicable to an ordinary shap'er operation "or' planing-operation-"it fin'ds 'i' ts in'ost advantageous expression '-'-i-n *a sharper operation adapted to form toothqikejportions :ena work pieceisuchfor-exampleas straight-or 'h'iieal teeth on*a"'cy1i1idrica1gear.

Inthe' preferred form "of th' invehtion th cut ting tool' comprises three main portions; firs't; 'a rigid 'support- "portion "second, 'a rlaitively movable '"po'rtion having cutting-edges harried there by: an'd thir'd, afieiiibie portion intermediate the other two -"portions anii adapted to iesrriitrialativemovement between the-cutting portions-arid the rigid supportportion.

The inventiontnciudes-a maehine for-carrying out *the process, a new "m'ethod of fiietal working-and aspeci'fid'to'ol.

*It' i's-'an obj ect' of thepreserit invention to '-provide a new method, machine' a'nd tool for carryingout a shaper eperationin-Whieh cuttingoiearanoe "is automatically provided --b'y -a relative movement. 'of th cutter upon initiation of "the cutting "stroke. It is -a-further object'of the invention to provide1alteriraftiveiyfor substantiali-y increased s eed in "the cutting :operation or substantiall greater accuracy ef the onshe'd prdduct in the sametimeas empleyed bymresent day conventional -'sh-api'ng operations. It is a further object 0f the present invention to provide for in'e-ta1 shap'in'g character lzed by the provision of a -shaver cutter whoseziite may bezs'ub- 'stantially in'creased hyfreversin'g' the shaper cutter 1 characterized further by' the-"provision: of a cutter '-f0r-'cutting 'he1ica1' parts adapted to perfor-m its-cutting operation 1 alternately on o ppositefs'ii e's of toothed members of *-a werk: piece; characterized by then'provis'idn o a disc-like-cutterhavin-g a rigid hubafid rim interconnected by a fie'X'-ib1e -'-web; characterized" further by a mahineadapted to perform cutting strokesin both directionsof"relativereeiprocationhetween a eutter and work piece; characterized fur'ther by a method or cutting employing a butter having identical cutting edg'es at "opposit ta'ces thereof in wmchmmn clearance for the trailing f ace is provided by 1-1161ina'tion of the cutter waiving the cutting stroke; and characterized 'fi-na'llvby arme'thod of cutting'shouider gears in -v'thich the cutter is inclined to a iear'ance position on' a cutting strokettowardfthe shoulder-arm movesfto 8 Glaim's.

aneutraiclearance' position on thereturnstroke. Other'obj ects and features of the inventionwiil become apparent as the description "proceeds, es-

companyi'ng drawings; wherein:

Figure 1 is a diagrammatic=view-"of afiiaehifie adapted to cairy-ofit thepreserrt inv'ehtion;

"Figure 2 is a -fragme'ntary, ma section shew irrg the improvedicutti-ng tooiasse b'iy; Figure Bis a'emgmmmamwiew1were fig the manner in" which *euain eleatanee is Vid -i Figure 4" is? -'adia'gra'mmatipvietv iiistrating he lateraldisplacementof'cuttingi eeth rel 'a'ih'elic'al Work piece-sofas"to provide for-c s alternatelyronnpposite sides-of th ceeth; a

Figure'h is a diagrammatic view' il lus'tratmg' the application of "the"p'r'esei1't inveritionto-fth cutting'ofshoiilder gears. Referringfirstto Figure 1, there-ismhJst-rated a "machine"'tOoFcompriSing "a"b'as e f0 av-mg mounted thereon'a work "support H A anwa 061 support "l2. Themahineisf the typaeom= lho'n'ly ferrd"to"fin gthe'fart a jsj'a (gear shape! and is gadafiteii'fto provide for reiativeruttin e'- ci'proe'ation betweenafctitter suhstahtiaily in form of a'gear,. e-afgearblarik in practice the cutter Wh'fl'e :b'eing recipm'catd axiauy iS fed into the sgear fielan to7ajpredete1mined epth While the cutter and:gearfhlank arvboth 1$" rotated; andthereafter;while"re1ative'retiproca+ tion'contihues, bdtiithe eutterraridthe gear 151 k are rotated slowly with the resliltthhLttheWeeth or the cutter generatercehwgateteethihh 'w'orkipiece. I V v ,j

A single motor 3 is fpibvifid"ivliicfififiifyffl of the parts, asxw'm ehe's cribea Thermotor 13 rotates'la shaft 4Tth'ro11ghsi'1itab'ie dr ving conneetions'l's'u'h as'fa'bl'tjlh, 'l'The sh'aftlf l a crank .il'itwhic-h' throuh afiinkl'! afi'd a ross; head 'I"8Ti's 'auafitedi to reciprocate I 2 TS male "f9 Whichcari'iesthetool'asseinbly 2'0.

The shaft l4 carries a he've ljgear 1'2! "which driv' es'a shaft-2 z thr'o'ughithe "medium or a flesh: ing-hevel vgearT'i-ifl and the-shaftfllhasj as its'ehii a-worml4 'd'ri'v'ssa TWi'fiLWhGFZB Th worm -whee12'5 cfr 'ivesfla pair "of 'mesh'ih'g" gears zfi andil throuh'the medium 6f bevl g. rs 28. The ,gear. 21'has-a shaft to IvvhichT'i's se 'ea' a worm-v30 meshing wit-ha -wor:m.wne1':a termed on the outer port-ion o'f .a{.lid1Ising' "32 lvvhi'chj'i's mounted for. rqtatiori in- 'beja ir ifigsl ifiaicati 15:33 The crosshead ;t8 previousiy referred" 1 driving connectionindicated ene ate at 351m reciprocatingthe spi n'dle -18, the conh ectio 35 permitting rotation 0f the spindle 4 9 r thereto. The :spindle l 9 is provided-with ga lindrical enlargement 38 which has teeth or splines thereon :engageable {in --corres pondin teeth :or' sp1'ines:39 tormed on theihterior of the housing 32. It'Wiil thushe apparent at;;r t tion 0f the housirig 432 through 'thQ:-rm;edi um;,oi its :worm =3 l'wvill result? inrazcorresp onding ota tion of the-spindle"! rid .the; tool assembly 20;. In the event tha earicarriedirbv theiwork support H is being uti w hrhas-straight teeth, the teeth or splines onithe'zienlargemehtfifl amid cutter teeth is somewhat greater, during the cutting operation, than would result from rocking about an axis locatedrcentrally of the cutter,

assembly 20 will be provided with aslow continuous rotation through the medium of its worm gear 31 and in addition a relative oscillation about its axis will be provided due to the reciprocation of the enlargement 38 and the "helical mating surfaces formed'on the member 38 and ,the'interior of the housing 32.

In'order to provide for an accurately timed rotation of the gear blank relative to the slow 7 timed rotation of the tool assembly 29, a bevel gear 40 is provided which meshes with a similar bevel gear carried by the shaft on which are mounted the gear 21 and the worm 30. The bevel gear 40 is connected to a cross shaft M which extends to the work support and rotates a housing through the medium of bevel gears 43, 44, matinggears 45, 46 and 41, worm 48 and worm gear 49. The work supporting spindle 50 is mounted for rotation in bearings indicated at and includes a chuck 52 for receiving the gear blank to be out.

It will be apparent that the machine structure thus far described does not provide any means for effecting a relieving motion of the tool relative to thework piece on the back stroke as is now conventional. In other words, the machine is adapted to effect a cutting stroke in both directions or relative reciprocation between the work piece and the tool assembly.

In order to effect cutting in both directions of reciprocation a cutter assembly as illustrated in detail in Figure 2 is provided. In this figure the cutter spindle is indicated at l9, which is shown as provided with'a threaded portion 6| on which engage clamping nuts 60 and 52. Between the clamping nuts 60 and 62 are provided the cutter 63 and a pair of annular abutment members 88., The cutter 63 is'provided with a central rigid hub portion 64 which engages over the spindle IS; an outer rigid annular rim portion 65, carrying cutting teeth or elements 65; and an intermediate annular thin flexible web 61 which permits relative movement between the hub 64 and the rim 65.

The web 51 is designed such that it will permit a relative rocking movement of the rim 65 about the center of the tool assembly C when the cutting portions 66 initially engage the work piece.

At the same time, the web 61 is of sufiicient thickness such that it prevents any other relative movement between the hub 64 and the rim 65. It will be appreciated that when the cutting operation being performed is a gear cutting operation, that the rocking movement of the rim 65 is about an axis which is perpendicular to the axis of the cutter assembly andperpendicular to the line joining the'center of the cutter assembly and the center of the gear blank and which passes substantially centrally through the cutter assembly.

By way of example, very successful gear cutting operations have been performed where the dimensions of the cutter 63 are approximately as follows: The thickness of the hub 64 is .500 inch, the thickness'of the rim 55 is .484 inch, the thickness of the webBT is .100 inch and the radial dimension of the web between the hub 6t and the i 65 is approximately 1.5 inches. In practice it is found that the inclination of the ends of the which is evidently due to some bending or deflection of the relatively stiff rim portion.

Rocking motion of the rim 65 of the cutter 83 about the center C is limited by faces 10 formed on the abutment members 68 and these faces are in the specific embodiment under discussion spaced from the adjacent faces of the rim by .008 inch. It will be appreciated that the foregoing figures have been given merely to enable those skilled int-he art to understand a successful embodiment-of the present invention and'are in no sense to be considered as limiting. As a matter of fact, it iscontemplated that the thickness 'of-the'web 6T may be between .075 and .125 inch and the spacing between the faces ill of the abutment members 68 or cooperating faces of the rim may be between .005and v.015 inch.

Attention is now directed to Figure 3, which'is V acdiagrammatic showing on an enlarged scale illustrating the manner in; which cutting clear,- ance is automatically provided. In this figure the rim 65 is illustrated in full lines in an inter mediate position equally spaced from the abutment surfaces E0 of the annular members 68. The cutting portion 66 is provided with cutting edges at opposite ends thereof, the tips of the cutting edges being indicated at 66a and 56b The profiles of the cutting edges are identical so that if the cutter assembly were reciprocatecl vertically the tips of both edges would follow, in the tracing indicated by the broken line-'13. -If now thecutter 63 is moved downwardly until its lower cutting edge having the corner 56b engages a work piece the rim 65 will rock about the centerjC until the rim fii engages the uppermost surface it of the annular member 68. At this time the corners fisct and 66b will have rocked about the center 0 to the position indicated in dotted lines and it will be observed thatthe corner 66a will now follow the trace i4 and the corner 662) will follow the trace 15. In other words, cutting clearance for the corner 66b in an amount indicated by the dimension d is provided. It will of course be apparent that in the case of a cutter having cutting portions 65 in the form of gear teeth, the cutting clearance provided at the sides of the teeth will be afunction of the angularity of these surfaces with radial planes. In other words, a portion of the cutter tooth surface which occupies a plane perpendicular to the radius of the cutter will have a maximum amount of cutting clearance. In like manner, a portion of the cutter tooth occupying a truly radial plane would be provided with no clearance by this rocking motion. In practice, however, there are no radial surfaces provided, so that some cutting clearance is provided in back of every portion of each of the cutting edges by the rockingmotion of the rim 65. In the event that none of the cutting edges approximate radial lines it may be that no additional cutting clearance need be provided. However, in some cases it may be desirable to modify the sides of the teeth as by hollow grinding so as to provide additional clearance directly in back of the cutting edge. In all cases, however, the cutting clearance for the trailing or inactive cutting edge will result solely from inclination of the cutter relative to the path of relative reciprocation.

In the case of the specific cutter whose 'dimensions were given above the tip of the cutter toothaiwas providedwith a hdllew whoseidepthiat its center midway I betweenwhe cutting-redgeszoi the tip was .001 inch and the sides df thetctitting teeth were prev-ide'd with a hollow 'whi'ch amounted to approximately 3002 finch midway between thecutting edges.

It is l desired to 1 emphasize, however, ithat in many eases no additi-onal kilearance l'cbe ground 'into the cutting teeth, with the 1 8811117 that an" extromelyinexpensive :cutterrresults, "the side surfaces of fhe cutting teeth being ground so '-''that #:ea'eh tooth .r is "of uni-term th iekness throughout.

'iIt is desired at this time' to m'enti'on 1a prime advantage of the present method 'of shaiiing. fit is inherent in this type of shaping where iti ls used'ito shaper eut gear 'tee'th thataa, mai-or ,portion" of the -ciitting action1'is done 'by 'the ieadi-ng corners of thecuttingteeth. In accordance with the presentinvention the cutter is reversible and sometime-motto dulling of the leading corners of the'cotter teeththe cutter ma'ybe teversedso that. the oppositeeorners of its teeth will become theiead-ing-corners iainc'r thus subjected to "the heaviestcuttin-gstrain.

It will 'be appreeiatedwhat cutting performed by this improved cutter may be substantiallytwioe as rapid conventional -cutting which takes place in one direction only-and in which-cutti-n'g' -strok is iollowed by' hack-out of the tool and a-return'idle stroke. "As aimatter of' fact, it is possible to reduce cutting time to somewhat "less '-'than half ot that previously *req-uird for the reason that some time is involvedin the backing out' of the tool iromthe work' pr-ior to v theidle' str'oke -and this'b'f course =is' -totail'ly aveided'inthe present-invention. H g

"If instead of employing the -cutterinam9mne toreduce'theedtting time to a *minimum, the

scri-bed herein in conjunction i with heli'cailly =tion of the work gear isindiea ted atQ hand et 8'2 there *is illustrated "a tooth space 1 in jwhieh the cdtter*tooth80 is -operated. "'It -wi1l-be -appreoiated that inthis operation the shaper *is one "in which the tool-spindle 19 has-"an-enlar'getit surf ace of ithe-gear blank iil theicutter will iroek about the' axis previously desci ibed until sueh time as the-rim of-the eutterengages the ab utment surfaces "Hithereabove. During-thisrook mg rnoeat or the-rim of the cutter,- arrzadditionaldslight rotation or the cutter assembly-"will resiiit'firorn the continued downward movement of the he]; portion thereof. This slight additional downward imevement wt the sh-db '-"=portion of ithe :ciitter resiiltsin iateral displacement 413i? the cutter too'th 51:0 the position iritiicate'd in matted lines at 80a, i which is will be sobservedts slightly oitset-withu'espect te -theitoOth space-"-82; fiontinuedi movement o! thetoothwfi "and lithe matting stroke will therfore remove metal =from the side otrthe' :toothslot' designa;ted 82a and there will bezolearance between the other side of the'rtooth ali'iand the other'side of the tooth 51013182. Wheni thetooth 80: passes -out of the other :en d ofithe tooth slot 82 -=and mressure between the work ipieoe Land the cutter reteased, ath'e' rim of the *eut-ter will l'immediately spring back to? its' intermediate position and the cutter -tooth*wi l'l=-a'gain*-align itself: with'iithe tooth spaeeaas 'iinc iicated at' 80b.

"In 'like' mannen'upon the i reverse stroke-fthe cutter tooth 188 will if'ollow the 'pathiof'thetooth space 83 until such time: a's' th'e other ':end.:of the cutter tooth 80 'engages' the flower" surfaceor athe blankat l ,at which time there'will' iollowasmall "lateral displacement tothe position indicated at 80c. In this position the I cutter :tooth 8011s effective to cut the 0thr'--,'Side 820 of -the"tooth slot, there being clearanoeibetweenvrtheiisidewof thetooth 80 and" the 'zside 'of the tooth :sp'ace 82a. This isia very deslrablefeature in :c-utting "helical gearsand Tone-which is inherent-trout the :use'zof a 'eutter shaving ithe ccharaeteristics idiselosed herein.

ReEerringinoWI to :flgure'1'5,'tthere:is illustrated a "method of ieuttingffs'houlder lgears whieh Yemplays *a mutter of the type idisclosed'iherein; i In this caseza lgeartblarikiiilfl'zoniwhiohiteeth'rs are tobe 'atormediandswvhichiihas af shou1der-i9'2' proaided: thereon adiiacentone ien'dsof the teeth :9 l iszb'eingrcutlby a eutter 939110ekablyfpositionediad- :jacentzanrabutmentM. Aswvillsbe observed from Figure:5,':rroeking motion "zo'f l the mutter 93 "into engagement-with'lthe abutmen't 94 tips thexentter blade 95 isoi'th'at the "upper :cuttin'g corner '96 is moved 'into 'sa '.'elearance ipositi'on :withzrespecflto thelowerrcuttingrcornenfl. iliponzoompletionioi the stroke, when the lower cutting corner '19.!

passesroutiof theitoothedportionr9110i:the blank, themexihle' web 9810! the '.cutter"=wi1l cause'ithe cuttertoiraissume a*neutralposition in which the corners 195 gand'I'Sl: are lin alignment with the Jdi-J "rection :of relative reciprocation "sand :clearance asi-ndicatedr at'le its: thus providedrforithe"return stroke. It will rb'e "observed rt-that in "this :case cuttingwtakesilplace1' only on :the down istrokenaof theircutt'er "assembly vand'i clearanee is automat icallysprovi'dedltor the r'eturn idle upper-"stroke. frhis-zclearanee, however, is provided automat- '-ieally .due *toi' -thefresi'lience of the :thin" web 198- and' therei'i's 'no Ynecessity'" iorib'aokin'g the 'eutter assembly-out oflthetooth islotras:iinipresentnonventionalifpractice.

;-In"::the 'latterio'ase whilexthe cutterportion has beennrindicated as "having upper Land-lower euttingaedges 96 iand 91;1t"willirberappreeiated thatii'f desired 'only -the' lowers surfaceiof-zthe cutting portion .95 :i-need "be '1 provided with cutting edges iami'fthat fm' back of these butting :edges the-fitooth-iieouid' ibe :bac'kecl off asidesiredt'to"proiride mutating *rblearance. However, Pit i=-is preferaliiento eprovtde: the itooth with 'eutting edges at opposite fiends 50f eeaeh cutting: toothcso that i the cutter :may :be 'c'reversed :as Lone :set of cutting edges -Jaecomesnduil. V

Niflhile: Irhave :described :invconsiderable "Edetail a specific machine rmethodrandrcuttertassembly vto iloeused-' in'zecmiunetioniwvith .thecshape m- 7; ting of gears,it will-be appreciated that-theginvention is of broader scope andis applicableto other types;of shaper-cutting such ,forexample as ordinary planing." It; will, further be appree ciated that the f. present: detailed description of my improved method, machine andtoolhas been given to enable those skilled in the art to prac:

'tice the invention-,; thescope of which is 'indicated by; the-appended claims."

.iWhat I claim ;as my inventioniszg: 5

,L-A machinefor shaper cuttinggears com-,- prising a rotary work support, a rotary rigid tool support, means, for reciprocating said tool supportin-cuttingstrokesparallel tovits axis, means for effecting agenerating rotation of said supports, cutting means on said tool supportcomprising an annular rim having outwardly vextending cutting teeth thereon, a flexible ,web connecting saidrini'to said tool support,;said web'occupying the planeof said rim, the flexibility of said' web permitting transverse tilting of at leastthatportionof said vrim carrying teeth engagedin cuttingmpon pressure appliedby resistance-tocutting, and spaced abutments carried; by said tool support limiting-tilting ,ofthe said portion of the rim.

2. A machine for shaper-cutting gears comprising a rotary work support, a rotary rigid tool support, means for reciprocating said tool supportin cutting strokesparallel to its axis,

means for effecting a generating rotation of said supports; cutting means on said tool support comprising an annular "rim having outwardly extending-cutting teeth thereon, a flexible web connectingtsaid rim to said tool support,- said web occupyingthe plane ofsaid rim; the flexibilityof said web permitting transverse tilting of at leasttthat portion of fsaidrimparrying teeth engaged in cutting upon pressure applied by resistance to cutting, and spaced ,abutments carried by said tool support limiting tilting of the said portion of the rim, said cutter support and web. constituting means for reciprocating said rim and preventing lateral bodily; movement thereof.; I 1

' 3: ,Mec'hanism for. shape'r cutting gears comprising a rotary work support, a substantially rigid rotary tool'support, drive means foreffecting relative reciprocation between said, supports in a direction parallel to the axis ofisaid tool support in identical paths on forward and reverse, strokes, meansfor effecting a generate ing rotation of said supports, cutting-means on said tool support comprising an annular fiexe ible resilient web extending radially outwardly from'saidto'ol support; an annular rim at the outer edge ofsaid web, cutting teeth extending outwardly-from said rim, said web being of a thickness selected in accordance with dimensions of said cutting means such as to'flex readily under cutting forces developed in a direction perpendicular to said web while preventing displacement of said cutting teeth in any direction .generally 'parallelto said web, the thick ness of said web'being' such as to require suppor'trfor that portion ofthe rim carrying v.the teeth engaged in cutting in. addition to the' support supplied by said webyand rigid abutment means at one side of saidrim adjacent tothe portion thereof carrying the teeth engaged in cutting to limit-displacement of the rim to, a predetermined amount and thereafter to supe port the cutting teeth against further displacementtduringa cutting stroke.- I I '4. Mechanism as defined in claim 3 in which s'aid abutment means "comprises a rigid ring carried bysaid tool support and spaced uniformly from saidirim., 5 Y -l g5.;Mechanism asdefined in claim 3 inpwhich said cutting teeth have cutting edges at both ends thereof, and rigid abutment means are provided .atboth sides of said rim to provide for cutting in botiydirections of reciprocation.

Mechanism as defined in claim 5 comprising helioalguide means associated-with said tool support to effect additional rotation thereof upon reciprocation, said cutting teeth being helical, whereby rocking of said teeth effectslimited rotational displacement thereof to provide varying depth of out upon cutting strokes in opposite directions. ,7

7. A gear shaper cutterfor use in cutting gears and the like, consisting of anannular hub portion having means for mounting said cutteron a tool support; an annular tooth] carrying rim portion spaced from said hub portion, a plurality of annularly spaced cutting teeth carried by said tooth carrying rim portion and 'posi tioned to out by relative jaxial reciprocation; of the cutter and the work, a flexible resilient web portion formed to extend co-extensively with said hub and'rim portions and joining said. portions, said web being of athickness selected in accordance with the cutting action such as to flex under cutting forces developed in a direction generallyperpendicular to said web while preventing displacement of said cutting teeth in any directiongenerally parallel :to said web during cutting; y

8. A gear shaperccutter -for use in cutting gearsand the like consisting of an annular hub portion having means for mounting said cutter on a tool support, an annular tooth carrying rim portion spaced from said-hub portion, a plurality of annularlyspaced cutting teeth carried by said tooth-carrying rim portion and positioned to cutby relative axial reciprocation of the cutter and the work, a flexible resilient web portion formed to extend co-extensively with said hub and rim portions and joining said portions, said web being of a thickness selected in accordance with the cutting action such as to flex under cutting forces developed in a direction generally perpendicular to said web while preventing displacement of said cutting teeth in any direction generally parallel to said web during cutting, and rigid abutment means at one sided said rim portion adjacent to the portion thereof carryingthe teeth engaged inputting to limit displacement of the rim portion to .a predetermined amount and thereafter to support the cutting teeth against further displacement during a cutting stroke.

WALTER S. PRAEGF REFERENCES orrsn The following references are of record in the 1-11 r this, patent; 7 V UNITED STATES PATENTS zNllfi'ibeli. 1; I

-Tr'. 'Na'me Date I 579,570 1 'Fellows Mar. 30, 1897 1,904,956 Simmons 'Apr. 18, 1933 "2,179,230 Hamilton i e Nov; 7, 1939 2,364,065 Frederichs Dec. 5, 1944 2,359,3 1, Marx Feb. 13, 1945 assas z; Pigott Oct. 9, 1945 2,405,337 Watefield Aug..6, 1946 Laesser Dec. 2,,1947 

